Essentially, the law defines the nature of that kind of work "employment". I.e. you have a rostered shift, provided a uniform, prescriptive work duties, staff-discount benefits. Generally long term.
Contrast to a specialist on a building site: provided their own tools, task/goal and deadline, but more or less autonomous (i.e. install the electrical wiring by Tuesday). Generally short or fixed term.
There are a lot of "traits" that the law indicates are employee or contractor traits for a contract.
Anecdotally, in my personal experience, the software industry is rife with abuse of this. Plenty of contractors bulking up a small team of employees for years.
Sorry, I meant after this change. As I understand it, you can just write in the contract they are a contractor and now they are and they can't challenge it. No sick leave, no annual leave, you want a job? Take it or leave it.